Patent Documents 1 and 2 describe in detail the disadvantages of conventional inactivated vaccines, toxoids, and the like, the present situations of development of mucosal vaccines and immunological adjuvants, etc.
As described in Patent Documents 1 and 2, it has been widely and deeply recognized that there is a need for a change from conventional vaccines for subcutaneous or intramuscular administration, for example, to mucosal vaccines that induce the production of IgA antibodies in mucosa, the route of natural infection with viruses. In particular, as next-generation vaccines for the 21st century, the development and commercialization of so-called mucosal vaccines that induce the production of IgA antibodies, local immunity, or mucosal immunity are wanted all over the world, but have not yet achieved.
To deal with these problems, the present inventors invented an antigen-and-drug (AD) vehicle that is a complex of pulmonary surfactant protein B and/or pulmonary surfactant protein C and a lipid(s), and also a mucosal vaccine comprising the AD vehicle and an antigen (Patent Document 1). The present inventors further found that the selective production of IgA antibodies and the production of both IgA and IgG antibodies are convertible by adjusting the weight ratio V/A between the AD vehicle amount (V) and the antigen amount (A), and have filed a patent application for a mucosal vaccine where such conversion is its mechanism of action (Patent Document 2). These Patent Documents 1 and 2 also disclose the effectiveness of fractions (peptides) of pulmonary surfactant proteins B and C.
Known examples of synthetic peptides associated with pulmonary surfactant proteins are those of Patent Documents 3 to 8.    [Patent Document 1] WO 2005/097182    [Patent Document 2] WO 2007/018152    [Patent Document 3] Japanese Patent No. 3009690    [Patent Document 4] JP-A-2004-305006    [Patent Document 5] JP-A-2006-504635    [Patent Document 6] WO 95/15980    [Patent Document 7] JP-A-2003-523348    [Patent Document 8] WO 02/32451